Pressure Distribution before and after O-Ring seal 1

[aetherTap]

Hey guys,

I'm modeling an adapter that will go inside of a pressure vessel holding 2500psi. The adapter is basically a cylindrical piece and it will be threaded into the wall of the pressure vessel. It will be submerged in water, thus bringing the need for various o-ring seals.

My question is - is there a good way for modelling the pressure distribution on the cylindrical faces before and after the oring seal? The area looks like this:

face O face
ring
---------^^^^^^^------------

maybe the left face would see 2500psig, and if the oring is holding up correctly, the back face will see 0psig? Is this a reasonable assumption when conducting an fea? I am simply concerned about the life of this adapter, but I am having trouble figuring out the most realistic distribution of this pressure. Thanks

 

[cbrn]

Hi,
if the O-ring seat has been designed correctly, then your assumption is correct and is commonly used in the field I work in (Hydraulic turbomachinery).
___
____|O|______
!
2500 ! 0 psi

You will have to check, after your FEA, that the deformations are not such as to "de-compress" the O-ring more than what is allowed for this pressure. O-ring manufacturers have tables or diagrams for that.

Regards

 

[cbrn]

Hi,
sorry, I didn't preview the post, so the "schema" was almost unreadable:

___
_____|O|______
!
2500 ! 0 psi

I hope now it is clearer.
Regards

 

[aetherTap]

thanks cbrn for that clarification..

I think my analysis is going very well! I modelled the contact faces before the oring to be node-to-node because they share the total face, but the small face after the o-ring is sharing a very deep surface so I modelled it as a surface contact. The displacement of the oring faces seem to be a resultant .001 in. I'm going to have look into it further but this preliminary analysis seems to be accurate.

 

[FEAHappy]

The oring will be pressurized at 2500 psi through the crossection. You could think of the oring as being a high viscosity liquid. The backside of the oring will have a pressure of 2500 psi pressing on the wall which is supporting the oring. The oring has very little strength.
The pressure of 2500 psi would be sufficient to cause the oring to assume the shape of the cavity. I worked on hydraulic pumps for 20 years.